Moisture detecting air cap indicator for expansion tank failure

ABSTRACT

Disclosed is an expansion tank having an internal cavity separated by a flexible diaphragm to form an upper pressurized gas portion and a lower pressurized fluid portion, and an indicator positioned at an upper part of the expansion tank in communication with the contents of the upper pressurized gas portion. The indicator is configured so as to display a first color if the operating conditions arc normal in the pressurized gas portion, and a second color if the amount of moisture detected in the pressurized gas portion greater than or equal to a predetermined amount. Further disclosed is a method for detecting whether there is an excessive amount of moisture in a pressurized gas portion of an expansion tank by allowing pressurized gas from the pressurized gas portion to come into contact with the indicator, and viewing the color displayed by the indicator. As such, the tank can be simply visually inspected to determine whether there is a potential failure in the tank.

FIELD OF INVENTION

The present invention generally relates to expansion tanks, and, moreparticularly, to diaphragm expansion tanks having an indicator to alerta user if moisture is present in the gas side of the expansion tank.

BACKGROUND

Expansion tanks are commonly used in heating, cooling and air conditionsystems to avoid unacceptable increase of system pressures duringheat-up, generally by absorbing expanding fluid and limiting pressurewithin the system. Expansion tank designs include open tanks, closedcompression tanks and diaphragm tanks.

In a diaphragm expansion tank, a diaphragm or bladder is used toseparate air from water within the tank. In particular, one side of thetank is connected to piping of a heating system (or cooling/aircondition system) and therefore contains the water, while the other sidecontains air under pressure. A Schrader valve is typically provided atthe air side of the tank for checking pressure and adding air, whichallows the pressure of the tank to be adjusted as needed.

An air/gas charge pressure on one side keeps the diaphragm at a distanceaway from the inside wall of the tank in the gas side. When the tank isinstalled onto a water system, the water system pressure pushes backagainst the diaphragm, compressing the gas. When the system is cold andthe water in the tank is at the minimum level, the tank pressure is atan initial/pre-charge pressure. As the temperature in the systemincreases, the water expands to compress the gas chamber via thediaphragm, causing an increase in the gas and water system pressure.

However, the diaphragm has a limited life. If eventually the diaphragm“bottoms out” on the tank wall, the tank becomes ineffective in thefunction it has been design to provide. Various failure modes forexpansion tanks include incorrect precharge pressure (e.g. a low airprecharge), excessive system pressure, diaphragm failure resulting inleak of air charge, and installation of an incorrectly sized tank (e.g.undersized tank which causes the diaphragm to overwork), all of whichcan lead to quick cycling and ultimately failure. In such failure modes,the diaphragm can develop a pinhole, an abrasion, a cut or the like thatallows water to enter the gas side of the tank. Over time, the gas willbe absorbed into the water system and the gas charge will decrease tozero. At this point, the tank is considered ineffective. This caneventually cause failure of other equipment in the system or failure ofthe tank itself, resulting in water leakage into space surrounding thetank.

In order to determine whether there are problems in the expansion tankoperation or if the expansion tank has failed, a homeowner must oftenrequire the services of a plumber to remove the tank from the system andperform tests. This is time consuming and expensive. It would, thus, bebeneficial to provide a mechanism that makes it easier for a homeowneror a plumber to determine whether an expansion tank has operationalproblems or has failed, thus enabling more pro-active maintenance of theequipment. Such a mechanism can also beneficially alert a user to earlyproblems in the tank, which can potentially be addressed to prevent tankfailure.

SUMMARY

The present invention provides an expansion tank which includes ahousing that has an upper end wall, a side wall, and a lower end wallthat together define a cavity. A flexible diaphragm extends within thecavity so as to separate the cavity into an upper portion, which issealed to contain a pressurized gas, and a lower portion, which issealed to contain a pressurized fluid. An indicator is positioned at theupper wall of the housing so as to visually alert a user if moisture ispresent in the pressurized gas side of the expansion tank.

According to one embodiment, the indicator is in the form of an air capindicator which is positioned in an upper end wall of the tank and incommunication with the pressurized gas side of the tank.

According to various embodiments, the indicator comprises an insert thatdisplays a first color. When in contact with a predetermined level ofmoisture or greater the indicator displays a second color Preferably,the predetermined level of moisture is a trace amount of moisture, andin some embodiments, the predetermined level of moisture is such thatwater droplets form and even a water volume exists. In yet furtherembodiments, the predetermined level of moisture is a level at whichmaterial (e.g., steel) forming the pressurized gas side of the tank willcorrode and rust.

According to various embodiments, the indicator further comprises a capat an upper portion, the insert at least partially disposed within thecap, and sidewalls extending downward from the cap to the upper end wallof the housing, wherein a gas tight and fluid tight seal is formedbetween the indicator and the upper end wall of the housing. Accordingto various embodiments, at least a portion of the cap is fabricated of atransparent material through which the insert is visible. At least aportion of the cap can be fabricated of an optically magnifyingmaterial, such that the cap insert is viewable and magnifiedtherethrough.

According to an embodiment, the cap is provided with a first color, andwhen the pressurized gas side of the tank is contacted with thepredetermined level of moisture or greater, the material forming thepressurized gas side corrodes and rusts. This corrosion and rust willthen deposit residue onto the surface of the cap. Alternatively, the capis provided with a first color, and at least a portion of the indicatoris fabricated of a material that is hydrochromic such that the firstcolor will change to the second color when contacted with thepredetermined level of moisture or greater. Preferably, this first coloris a light color that will contrast with the second color and with rust,which is typically red-orange-brown-color. According to a preferredembodiment, the cap is a bright white color, which provides a sharpcontrast with deposited rust. The bright white, or other color, of thecap can be provided either by the material itself forming the cap (e.g.using a white plastic material that is formed into the cap) or bycoloring the cap with the desired bright white or other color.

According to various embodiments, at least a portion of the insert iscoated with a hydrochromic ink. The hydrochromic ink displays the firstcolor. The hydrochromic ink becomes clear when contacted with thepredetermined level of moisture or greater and therefore the secondcolor is displayed.

According to various embodiments, the insert is of the first color. Whena predetermined amount of moisture or greater exists, rust deposits formon the first color to indicate a second color. In a further embodiment,water droplets or even a water volume can be seen through the clearportion of the cap where the insert if visible.

According to various embodiments, the indicator is disposed to enclose avalve on the upper end wall of the housing, the valve being incommunication with the pressurized gas in the upper portion of thecavity.

In another embodiment, a method is provided for indicating a failure inan expansion tank comprising a flexible diaphragm, where the flexiblediaphragm divides the tank into a pressurized gas side and a pressurizedfluid side. An indicator is positioned in an upper end wall of theexpansion tank and in fluid communication with the pressurized gas side,e.g. via a valve. The indicator includes a cap having a cap insertdisposed therein. In particular, the cap has a domed portion (“capdome”), at least a portion of which is clear so that a user can view thecontents therein. The cap insert is designed so as to display a firstcolor when the pressurized gas side of the tank is at its normaloperating condition. and to display a second color when exposed to apredetermined level of moisture or greater In order to test theexpansion tank, the valve is actuated to allow pressurized gas from thepressurized gas side of the tank to enter the cap dome and come intocontact with the cap insert. If the pressurized gas side of the tank hasbeen exposed to or contains a detectable level of moisture, then the capdisplays the second color to indicate either problems with or failure ofthe expansion tank. If the pressurized gas side of the tank has not beenexposed to or does not contain a detectable level of moisture, then thecap insert will display the first color to indicate that the expansiontank is operating properly. Preferably, the predetermined level ofmoisture is a trace amount of moisture, in some embodiments, thepredetermined level of moisture such that water droplets form and even awater volume exists, and in yet other embodiments, the predeterminedlevel of moisture is a level at which material (e.g., steel) forming thepressurized gas side of the tank will corrode and rust.

Additional objects and advantages of the invention will be set forth inpart in the description which follows, and in part will be obvious fromthe description, or may be learned by practice of the invention. Theobjects and advantages of the invention will be realized and attained bymeans of the elements and combinations disclosed herein, including thosepointed out in the appended claims. It is to be understood that both theforegoing general description and the following detailed description areexemplary and explanatory only and are not restrictive of the inventionas claimed. The accompanying drawings, which are incorporated in andconstitute a part of this specification, illustrate several embodimentsof the invention and, together with the description, serve to explainthe principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1. is a cross-sectional view of an example pre-pressurizedexpansion tank with an indicator;

FIG. 2 is a cross-sectional view of the example expansion tank of FIG. 1partially filled with a fluid;

FIG. 3 is a cross-sectional view of the example expansion tank of FIG. 1filled with a fluid;

FIG. 4 is a cross-sectional view of the example expansion tank of FIG. 1in a failure mode with an under-pressurized gas section.

FIG. 5 is an enlarged cross-sectional view of a portion of the exampleexpansion tank of FIG. 1;

FIG. 6A is an enlarged cross-sectional view of the example indicatorshown in FIG. 1 in the normal operating position; and

FIG. 6B is an enlarged cross-sectional view of the example indicatorshown in FIG. 6 in the alert/failure position.

It should be understood that the appended drawings are not necessarilyto scale, presenting a somewhat simplified representation of variouspreferred features illustrative of the basic principles of theinvention. The specific design features of the present invention asdisclosed herein, including, for example, specific dimensions,orientations, locations, and shapes will be determined in part by theparticular intended application and use environment.

In the figures, reference numbers refer to the same or equivalent partsof the present invention throughout the several figures of the drawing.

Definitions

To facilitate an understanding of the present invention, a number ofterms and phrases are defined below.

As used herein, the singular forms “a”, “an”, and “the” include pluralforms unless the context clearly dictates otherwise. Thus, for example,reference to “a sensor” includes reference to more than one sensor.

Unless specifically stated or obvious from context, as used herein, theterm “or” is understood to be inclusive.

The term “including” is used herein to mean, and is used interchangeablywith, the phrase “including but not limited to.”

As used herein, the terms “comprises,” “comprising,” “containing,”“having” and the like can have the meaning ascribed to them in U.S.Patent law and can mean “includes,” “including,” and the like;“consisting essentially of” or “consists essentially” likewise has themeaning ascribed in U.S. Patent law and the term is open-ended, allowingfor the presence of more than that which is recited so long as basic ornovel characteristics of that which is recited is not changed by thepresence of more than that which is recited, but excludes prior artembodiments.

As used herein an “excessive” amount of moisture means any moisturepresent in the pressurized gas side of the tank as a result of acompromised diaphragm.

As used herein a “predetermined level of moisture or greater” is onewhich causes the cap to change from one color to another color, such asby causing a hydrochromic ink to change color, or by causing a material(e.g., steel) forming the pressurized gas side of the tank to corrodeand rust or by allowing water droplets or a water volume to be present.Such a predetermined level can include in some embodiments a traceamount of moisture, or in other embodiments any amount of moisture suchthat water droplets form and even a water volume exists

Unless specifically stated or obvious from context, as used herein, theterm “about” is understood as within a range of normal tolerance in theart, for example within 2 standard deviations of the mean. About can beunderstood as within 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%,0.1%, 0.05%, or 0.01% of the stated value. Unless otherwise clear fromcontext, all numerical values provided herein are modified by the termabout.

Ranges provided herein are understood to be shorthand for all of thevalues within the range. For example, a range of 1 to 50 is understoodto include any number, combination of numbers, or sub-range from thegroup consisting 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16,17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34,35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, or 50.

Any devices, components, apparatus, or methods provided herein can becombined with one or more of any of the other devices, components,apparatus, and methods provided herein.

DETAILED DESCRIPTION

Incorrect installations of well/expansion tanks, as well as incorrectgas pre-charging and gas loss failures, may lead to eventual tankfailures that may cause water to leak from the tank. Tank under sizingalso results in more stress on the tank and can result in prematurefailure of the tank. The present invention provides an indicator for anexpansion tank that can alert a user to a problem with the system,before a tank failure or leak occurs, and/or at any time after a tankfailure or leak occurs. In particular, the present invention provides anindicator that displays a first color when the tank is operating undernormal operational conditions (i.e., wherein no moisture or anundetectable level of moisture is present on the gas side of the tank),and that displays a second color when problems with the tank have beendetected (i.e., wherein any moisture or a detectable level of moistureis present in the gas side of the tank). This provides a visual aidindicating problems with the tank and can be used to indicate ifmaintenance or replacement of the tank is required.

Referring now to FIGS. 1-4, an exemplary pre-pressurized expansion tank10 is shown. It is noted that the general features of the expansion tank10 can be in accordance with known expansion tanks, and the exemplaryexpansion tank 10 shown in the figures is one example thereof. Thefeatures of the expansion tank 10 depicted in the figures are similar tothose shown in U.S. Pat. No. 5,386,925, issued Feb. 7, 1995, andentitled Expansion Tank and U.S. Pat. No. 7,032,628, issued Apr. 25,2006, and entitled Mobile Prepressurized Diaphragm Type Fluid StorageTank, both of which arc incorporated herein by reference.

In the example shown herein, the tank 10 has a housing 11, formed by anupper housing 12 and a lower housing 13, that defines an internal cavity14. A deformable diaphragm 16 and a liner 18 are positioned within thecavity 14 and are removably attached to the lower housing 13, forexample, by a retaining ring 20 or the like. An indicator 30 ispositioned at a top portion of the upper housing 12 as is described inmore detail below.

The upper housing 12 has a generally cylindrical side wall 22 and an endwall 24. The upper housing 12 can be of any size depending on thedesired total volume of tank 10 and can be of the same general design asthe lower housing 13. A conventional valve 50, such as a “Schrader”valve or the like, is preferably provided in the end wall 24 of theupper housing 12 to allow the addition or removal of air (gas) to/fromcavity 14 for pressurizing the tank 10.

The lower housing 13 also has a generally cylindrical side wall 26 andan end wall 28. The lower housing 13 can also be of any size dependingon the desired total volume of tank 10. A fitting 32 is provided in endwall 28 of lower housing 13 to allow water to flow into and out of thetank 10. As best shown in FIG. 5, the sidewall 26 can have a concavegroove 34 formed around its circumference, which can mate with groovesformed in the diaphragm 16, liner 18 and retaining ring 20, as describedbelow. The sidewall 26 can further have an inset portion 36 (as bestshown in FIG. 5) formed at an end of the sidewall 26, which creates anoverlap joint with the sidewall 22 of the upper housing 12 when the tank10 is assembled. Once assembled, the upper housing 12 can be welded orotherwise secured to the lower housing 13.

The upper and lower housings 12, 13 and retaining ring 20 can be made ofany suitable material capable of withstanding the pressure desired andcompatible with the fluids to be stored and dispensed. High strengthstructural steel is one conventional material that has been used formaking the upper and lower housings 12, 13 and retaining ring 20 andallows the upper and lower housings 12, 13 to be joined together by awelding process. However, a mechanical joint also can be used to joinupper and lower housings 12, 13 which can be formed of any materials, aslong as it provides a structural hermetic seal.

As shown the figures, the retaining ring 20 is arcuate with a concaveouter portion and a convex inner portion, which corresponds to and mateswith the groove 34 in the sidewall 26, the groove 17 in the diaphragm16, and the groove 19 in the liner 18, as described in more detailbelow, to anchor the diaphragm 16 and liner 18 in place and provide awater and gas tight seal.

The diaphragm 16 is flexible and is preferably made of an elastomer,such as butyl rubber, and is disposed inside of the lower housing 13. Asshown in FIG. 5, the diaphragm 16 has an inwardly protruding groove 17adjacent its end and is situated so that its end is adjacent the end ofliner 18. As such, the groove 17 corresponds to and mates with thegroove 34 of the lower housing 13 and the retaining ring 20 tomechanically lock or secure the diaphragm 16 to the lower housing 13.According to various embodiments, the diaphragm 16 is preferably moldedto conform to the inner shape of lower housing 13. Thus, the diaphragm16 is compressed between retaining ring 20 and sidewall 26 of lowerhousing 13, forming a hermetic seal against air and the fluid.

The liner 18 is preferably made of a liquid-impervious material, such aspolypropylene, and is disposed to cover the inner surface of the lowerhousing 13. As shown, the liner 18 is positioned between the lowerhousing 13 and diaphragm 16. The liner 18 also preferably has aninwardly protruding groove 19 adjacent its end and is situated so thatits end is adjacent the end of the diaphragm 16. As such, the groove 19corresponds to and mates with the groove 34 of the lower housing 13 andretaining ring 20 to mechanically lock or secure liner 18 to the lowerhousing 13. Thus, the liner 18 is compressed between retaining ring 20and sidewall 26 of the lower housing 13, forming a hermetic seal againstair and the fluid.

The portion of the cavity 14 disposed between the liner 18 and diaphragm16 forms a water receiving portion of cavity 14. The water is, thus,contained between liner 18 and diaphragm 16 so that the entire innersurface of upper and lower housings 12, 13 is shielded from the water.As a result, corrosion of the tank 10 can be prevented. Thisbeneficially allows construction of the tank 10 from any desiredmaterial, without regard to the effect of water on that material. Asshown in FIGS. 1-4, the liner 18 also has an aperture that aligns withfitting 32 and provides a liquid tight seal with fitting 32 to preventwater in the tank 10 from flowing between the liner 18 and fitting 32.

As shown generally in FIGS. 1-4, an indicator 30 is provided in the endwall 24 of the upper housing 12 of the tank 10. The indicator 30 is incommunication with the contents of the cavity 14, particularly thecontents of the cavity 14 positioned above the diaphragm 16. In otherwords, the indicator 30 is in communication with the pressurized gasportion, which is between the upper end wall 24 and the diaphragm 16.

According to an exemplary embodiment as shown in the figures, theindicator 30 is in communication with the valve 50 so as to allow thecontents of the tank to come into contact with the indicator 30 via thevalve 50. For example, as shown in the figures, the indicator 30 may beconfigured to cover or enclose a portion of the valve 50 on the exteriorsurface of the tank 10. Preferably, the indicator encloses the valve 50on the exterior surface of the tank 10 such that actuation of the valve50 to expels the contents (pressurized gas) of the tank 10 positionedabove the diaphragm 16 results in the pressurized gas entering theindicator 30 and being contained therein.

According to an embodiment, the indicator 30 is installed in connectionwith the tank 10, preferably in connection with the valve 50, in such away that an air-tight seal is formed between the indicator 30 and thetank 10. As such, leakage of gas and liquids into the indicator 30(i.e., from the external atmosphere) and out of the indicator 30 (i.e.,into the external atmosphere) is prevented. For example, the indicator30 may include one or more seals to ensure an air-tight seal between theindicator 30 and the tank 10 such that contents of the tank will notleak out through the indicator 30 over time.

According to various embodiments, the indicator 30 can be configured soas to display a particular color when the amount of moisture in thepressurized gas side of the tank 10 is within acceptable limits, and todisplay a different color when the amount of moisture is aboveacceptable limits. For example, the indicator 30 can display a colorthat will stand out from the other nearby components of the tank 10(e.g., red, orange or the like) when the amount of moisture in thepressurized gas side of the tank 10 is above acceptable limits. On theother hand, when the amount of moisture in the pressurized gas side ofthe tank 10 is within acceptable limits, then the indicator 30 willdisplay a different color. For example, the different color may, forexample, be any color similar to nearby components of the tank 10 so asto blend in (e.g., black, grey, silver, white, etc.). Thus, theindicator 30 provides a user with a simple visual mechanism by which itcan be determined whether or not there are operational problems in thetank 10. Such a simple visual mechanism can alert a user to earlyproblems present in the tank 10 that can potentially be addressed byroutine maintenance, thereby potentially avoiding further failure of thetank 10 that may result is system performance reduction or subsequentsystem component failures. Further the visual mechanism can alert a userto tank failure, thereby allowing a user to replace a failed tank in amore timely manner.

The indicator 30 can be of any configuration that will cover or encasethe portion of the tank 10 (e.g. valve 50 on the exterior of the tank10) and that will allow the contents of the tank expelled from the valve50 to enter the indicator 30 and be contained therein. For example, theindicator 30 can have an overall dome-like shape (such as that shown inFIGS. 6A-B), box-like shape, cylindrical shape, cone-like shape, etc.

As shown in the exemplary embodiment in FIGS. 6A-B, the indicator 30includes an upper cap 40, side walls 46 extending from the cap 40 andengaging the outer surface of the tank 10, and a cap insert 42 at leastpartially disposed within the cap 40. The cap 40 can have a generallydomed rounded structure as shown in the figures, or it can be of anyother configuration that allows it to contain at least a portion of thecap insert 42 therein.

At least a portion of the indicator 30 is fabricated of a transparentmaterial through which a user can view the contents of the indicator 30.In particular, the indicator 30 is fabricated of a transparent materialin at least a portion that allows a user to clearly view the cap insert42. For example, the entire cap 40 can be made transparent, as shown inFIG. 6B so as to allow easy and unobstructed viewing of the cap insert42 therethrough. As shown in FIG. 6B, the remainder of the indicator 30,such as the side walls 46, can be fabricated of a non-transparentmaterial, or can be fabricated of a transparent material, if desired.

According to embodiments of the present invention, at least a portion ofthe cap insert 42 is fabricated so as to display a second color when itis exposed to predetermined levels of moisture or to display water if awater volume is present, and to display a first color when it is undernormal operating conditions. In general, there should not be anymoisture present within the pressurized a gas side of the tank 10 and,thus, no level of moisture or only a trace level of moisture isacceptable. In some embodiments, an “acceptable” level of moisture isthe level below that which is detectable by the cap insert 42 in orderto trigger the cap insert 42 to change color.

For example, at least a portion of the cap insert 42 can be fabricatedso as to display a first color when it is exposed to no moisture or lessthan detectable levels of moisture, and to display a second color whenit is exposed to any level of moisture greater than about zero (e.g.,detectable levels of moisture). As such, a user can simply view the capinsert 42 through the cap 40 to determine the color of the cap insert 42and, as a result, be alerted as to the functioning of the tank 10.

According to an embodiment, the cap 40 is fabricated of material thatoptically magnifies the contents of the cap 40 viewed therethrough. Assuch, one can more easily view the cap insert 42 and see the color so asto determine whether the tank 10 is “good” or “faulty”.

According to an exemplary embodiment, the cap insert 42 has an upperportion 44, which can be dome-like in shape as shown in FIG. 6B, thatprojects into the cap 40 portion of the insert 30. The upper portion 44is configured and disposed within the cap 40 so as to be clearly visiblethrough the cap 40.

According to one preferred embodiment, at least a portion of the capinsert 42 (e.g. the upper portion 44 which is visible through the cap40) is formed to have a first color which is the color that indicatesthat the tank is functioning properly. When the pressurized gas side ofthe tank 10 is exposed to moisture, material forming the pressurized gasside of the tank 10 will corrode and rust. This corrosion and rustpresent in the internal environment will quickly deposit rust residueonto the surface of the cap insert 42. As such, the first color of thecap insert 42 is preferably one which is in contrast with the color ofdeposited rust, which is typically a red-orange-brown-color. Accordingto a preferred embodiment, the cap insert 42 is a light color such as abright white color, which provides a sharp contrast with deposited rust.The bright white or other color of the cap insert 42 can be provided byany conventional method. In some embodiments, the material forming thecap insert 42 (or a portion of the cap insert 42, such as the upperportion 44, visible through the cap 40) can itself be one which is thedesired first color. For example, the cap insert 42 or portion thereofcan be molded or otherwise formed from a white or other colored plasticmaterial into the desired shape. Alternatively, the cap insert 42 can beformed of any material of any color and can be subsequently colored asdesired.

According to other embodiments, at least a portion of the indicator 30which is in communication with the cap insert 42 is formed of a materialthat will corrode and rust when exposed to moisture. This makes itpossible to form the tank 10, including the pressurized gas side, of amaterial that is resistant to corrosion. In such embodiments, the tank10 is tested so as to allow pressurized gas from the pressurized gasside of the tank to enter to indicator 30. If moisture is present in thepressurized gas, it will corrode and rust the portion of the indicator30. This corrosion and rust present in the internal environment of theindicator 30 will quickly deposit rust residue onto the surface of thecap insert 42. A further embodiment is that water droplets or a watervolume will accumulate in between the cap insert 42 and the cap 40 whereit will be visible in the upper portion 44.

According to some embodiments, at least a portion of the cap insert 42visible through the cap 40 (e.g. the upper portion 44) is coated with ahydrochromic ink. Hydrochromic inks are well known and will not bedescribed in great detail herein. Rather, such known hydrochromic inkscan suitably be used.

For example, in one embodiment, the hydrochromic ink can display a firstcolor when it is in normal operating condition. and can display a secondcolor when it is in contact with a predetermined amount of moisture orgreater (e.g. a detectable level of moisture, such as greater than tracelevels of moisture or greater than zero moisture). As such, the upperportion 44 (or other desired portion of the cap insert 42) can simply becoated with the hydrochromic ink. Any contact of the hydrochromic inkcoated portion with the predetermined amount of moisture or greater willresult in the ink displaying the second color, indicating problems withthe tank. The second color is preferably any color that will stand outto a user, for example, red, orange, etc. The second color can be anycolor different than the first color (e.g. white, silver, grey etc.).

In another embodiment, the hydrochromic ink can display the first colorwhen it is in contact with less than the predetermined amount ofmoisture, and can become transparent when it comes into contact with thepredetermined amount of moisture or greater. As such, the upper portion44 (or other desired portion of the cap insert 42) can be coated withthe second color that alerts a user when there is a problem with thetank (e.g. excessive moisture/any amount of moisture). The second colorcan then be coated with the hydrochromic ink. Any contact of thehydrochromic ink coated portion with the predetermined amount ofmoisture or greater will result in the ink becoming transparent tothereby reveal the second color.

According to an exemplary embodiment, the upper portion 44 of the capinsert 42 is provided with a white band (or any other color differentthan the second color) of hydrochromic ink radially around the capinsert 42. When the white band remains white (or the other colordifferent than the second color) then the tank is considered to be“good” (i.e., no moisture/acceptable levels of moisture present in thepressurized gas side of the tank 10). If water leaks into thepressurized gas side of the tank 10, the water will make its way intothe cap 40 of the indicator 30 through the valve 50 together with thepressurized gas (or other means through which pressurized gas exits thetank 10). The pressurized gas containing the water enters into the cap40 and comes into contact with the hydrochromic ink on the cap insert42. If water is present in the pressurized gas, then the water will turnthe hydrochromic ink invisible, revealing the second color (e.g. red)underneath (or will change the color of the hydrochromic ink to thesecond color). The change in color (e.g., from white to red) willindicate that the tank 10 has water on the pressurized gas side of thediaphragm 18 and has failed.

According to a preferred embodiment, the cap insert 42 is colored asecond color and is then coated with a hydrochromic ink of a first colorthat (1) becomes transparent to reveal the second color beneath it whencontacted with the predetermined amount of moisture or greater, andreturns back to the first color once the moisture has dried out, or (2)changes to the second color when contacted with the predetermined amountof moisture or greater, and returns back to the first color once themoisture has dried out. As such, the indicator 30 is reusable and, thus,does not need to be replaced once it has come into contact with moistureand has changed color.

As shown in FIG. 6A, the indicator 30 can be designed to have twoplastic molded gaskets, which act as a primary seal 47 and a secondaryseal 48. The various parts of the indicator 30 can be formed through anymethod, such as molding and the like. Preferably, the cap 40 is moldedto form a transparent material and the cap insert 42 is molded in anatural or white color and is thereafter colored with the second colorand the first color. The various components can be assembled andattached using sonic welding or similar methods that will ensure a goodhermetic seal is made.

As shown in FIG. 6A, the primary seal 47 may be disposed at an upperlocation of the indicator 30 between the cap insert 42 and the valve 50so as to form a seal between the end of the valve 50 and the upperportion 44 of the indicator 30. The secondary seal 48 can be disposed ata bottom part of the indicator 30 between the valve 50 and the topsurface of the tank 10 to provide a seal therebetween that will preventpassage of gas and liquids between indicator 30 and the exterior of theindicator 30.

In order to test the tank 10, the valve 50 is actuated to allowpressurized gas inside the tank 10 to enter the indicator 30,particularly to enter the cap 40 and come into contact with the capinsert 42. If the pressurized gas within an acceptable level then thecap insert 42 remains unchanged in color. On the other hand, if moistureis present in the pressurized gas above an acceptable level, then thecap insert 42 changes color.

According to an exemplary embodiment, the cap insert 42 or portionthereof is a first color and at least a portion of the pressurized gasside of the tank 10 is fabricated of a material that corrodes and rustswhen contacted with moisture. According to another exemplary embodimentthe cap insert 42 or portion thereof is a second color and at least aportion of the indicator 30 which is in communication with the capinsert 42 is formed of a material that will corrode and rust whenexposed to moisture. In such embodiments, if moisture is present in thepressurized gas side of the tank 10, the material forming thepressurized gas side of the tank 10 or the cap insert 42 will corrodeand rust when exposed to the pressurized gas containing the moisture.This corrosion and rust present in the internal environment will quicklydeposit rust residue onto the surface of the cap insert 42. Thisdeposited rust changes the color of the cap insert 42, thus indicatingthat there is an excessive amount of moisture in the pressurized gasside of the tank 10. If the moisture in the pressurized gas is within anacceptable level, then the corrosion and rusting does not occur and thecolor does not change from the first color, indicating that the amountof moisture in the pressurized gas side of the tank 10 is acceptable.

According to another exemplary embodiment, the cap insert 42 is coloreda second color (e.g. red) and is then colored a first color using ahydrochromic ink. If moisture is present in the pressurized gas above anacceptable level, then the hydrochromic ink becomes transparent and thecap insert 42 changes color to the second color to indicate that thereis an excessive amount of moisture in the pressurized gas side of thetank 10. If the moisture in the pressurized gas is within an acceptablelevel, then the hydrochromic ink does not change, and the cap insert 42displays the first color to indicate that the amount of moisture in thepressurized gas side of the tank 10 is acceptable.

The present design helps a homeowner and/or plumber to visually inspectthe tank 10 on a more regular basis without having to remove the tank 10from the system. As such, the plumber or homeowner can be morepro-active with maintaining the equipment being used. The presentindicator 30 can also beneficially adapt easily to any existing tankhaving a common valve, e.g. a Schrader style air valve, which is presenton all expansion tanks. As such, the indicator 30 can be simply attachedto the tank 10 about the valve 50 without requiring any modification tothe tank 10 design itself

Furthermore, according to various embodiments, the indicator may beadapted with the appropriate electronics/software to forward an alert toan email address, cellular phone, or smart phone to alert the user ifmoisture has been detected.

While particular embodiments of the present invention have been shownand described, it will be obvious to those skilled in the relevant artsthat changes and modifications may be made without departing from theinvention in its broader aspects. Therefore, the aim in the appendedclaims is to cover all such changes and modifications that fall withinthe true spirit and scope of the invention. The matter set forth in theforegoing description and accompanying drawings is offered by way ofillustration only and not as a limitation. The actual scope of theinvention is intended to be defined in the following claims when viewedin their proper perspective based on the prior art.

1-13. (canceled)
 14. A tank comprising: a housing defining a cavity andbeing formed of a material that corrodes and rusts when in contact witha pressurized fluid; a flexible member positioned within the cavity andconnected to the inner wall of the housing, the flexible memberseparating the cavity into a first portion sealed to contain apressurized gas and a second portion sealed to contain the pressurizedfluid, an indicator connected to the housing in communication with thepressurized gas in the first portion of the cavity, the indicatorincluding a cap and an insert disposed within the cap, the cap beingconnected to an outer surface of the housing and including a transparentportion, and the insert including a display portion that is a firstcolor and that extends into and is spaced from the transparent portionof the cap to form with the cap an area for receiving the pressurizedgas and/or fluid, wherein when the pressurized gas is free of thepressurized fluid, the first color of the insert is visible, and whereinwhen the pressurized gas includes a level of pressurized fluid thatcauses the material of the housing to corrode and rust, the pressurizedfluid will be a second color visible through the transparent portion.15. The tank according to claim 14, wherein the transparent portion ofthe cap is formed of a material that optically magnifies the contents ofthe cap.
 16. The tank according to claim 14, further including a sealbetween the outer surface of the housing and the indicator that preventspressurized gas and/or fluid from the cavity from leaking to anenvironment through the indicator.
 17. The tank according to claim 14,further including a valve at least partially enclosed by the indicatorand in communication with the first portion of the cavity and theindicator such that pressurized gas and/or fluid expelled from the valveenters the indicator.
 18. The tank according to claim 17, wherein thevalve includes a valve body and a valve stem, wherein the valve body isconnected to the insert and a ledge of the insert is configured toactuate the valve stem to allow the pressurized gas to enter the area.19. The tank according to claim 18, wherein the valve body includesthreads on an outer surface thereof and the insert includes threads onan inner surface thereof that mate with the threads on the valve body.20. The tank according to claim 18, furthering including a seal betweenthe valve body and the insert.
 21. The tank according to claim 17,further including a seal between the outer surface of the housing, thevalve, and the indicator that prevents pressurized gas and/or fluidexpelled from the valve from leaking to an environment.
 22. The tankaccording to claim 14, wherein the indicator has a dome-like shape. 23.A tank comprising: a housing defining a cavity; a flexible memberpositioned within the cavity and connected to an inner wall of thehousing, the flexible member separating the cavity into a first portionsealed to contain a pressurized gas and a second portion sealed tocontain a pressurized fluid; an indicator connected to the housing incommunication with the first portion of the cavity, wherein a firstcolor is visible through the indicator when the pressurized gas has alevel of moisture below a predetermined level, and a second color isvisible through the indicator when the pressurized gas has a level ofmoisture at or above the pressurized level; and a valve at leastpartially enclosed by the indicator and in communication with the firstportion of the cavity and the indicator such that pressurized gasexpelled from the valve enters the indicator.
 24. The tank according toclaim 23, wherein the indicator includes a cap sealed to an outersurface of the housing and an insert at least partially disposed withinthe cap, and wherein an area is formed between the cap and insertdefining a space for the pressurized gas.
 25. The tank according toclaim 24, wherein the valve includes a valve body and a valve stem,wherein the valve body is connected to the insert and a ledge of theinsert is configured to actuate the valve stem to allow the pressurizedgas to enter the area.
 26. The tank according to claim 25, wherein thevalve body includes threads on an outer surface thereof and the insertincludes threads on an inner surface thereof that mate with the threadson the valve body.
 27. The tank according to claim 25, furtheringincluding a seal between the valve body and the insert.
 28. The tankaccording to claim 24, wherein at least a portion of the cap is formedof a material that optically magnifies the contents of the cap.
 29. Thetank according to claim 23, further including a seal between the outersurface of the housing, the valve, and the indicator that preventspressurized gas expelled from the valve from leaking to an environment.30. A tank comprising: a housing defining a cavity and being formed of amaterial that corrodes and rusts when in contact with a pressurizedfluid; a liner positioned within the cavity and connected to an innerwall of the housing; a flexible diaphragm positioned within the cavityand connected to the inner wall of the housing, the diaphragm separatingthe cavity into a first portion sealed to contain a pressurized gasbetween the inner wall and the flexible diaphragm, and a second portionsealed to contain the pressurized fluid between the liner and theflexible diaphragm; a valve extending through the housing into the firstportion of the cavity; and an indicator connected to the housing andsurrounding the valve, the indicator being in communication with thepressurized gas in the first portion of the cavity via the valve and theindicator including a cap and an insert disposed within the cap, the capbeing connected to an outer surface of the housing and including atransparent portion, and the insert including a display portion that isa first color and that extends into and is spaced from the transparentportion of the cap to form a space for receiving the pressurized gasand/or fluid, wherein when the pressurized gas is free of thepressurized fluid, the first color of the insert is visible though thetransparent portion of the cap, and wherein when the pressurized gasincludes a level of pressurized fluid that causes the material of thehousing to corrode and rust, the pressurized gas and pressurized fluidwill enter the space and be a second color visible through thetransparent portion of the cap.
 31. The tank according to claim 30,wherein the valve includes a valve body and a valve stem, wherein thevalve body is connected to the insert and a ledge of the insert isconfigured to actuate the valve stem to allow the pressurized gas toenter the area.
 32. The tank according to claim 31, wherein the valvebody includes threads on an outer surface thereof and the insertincludes threads on an inner surface thereof that mate with the threadson the valve body.
 33. The tank according to claim 31, furtheringincluding a seal between the valve body and the insert.